JP4542992B2 - Residual heat removal system and operation method thereof - Google Patents

Description

  The present invention relates to a residual heat removal system used when a boiling water reactor is shut down and when a coolant loss accident occurs, and an operation method thereof.

  The residual heat removal system for boiling water reactors functions as an emergency core cooling system in the event of a loss of coolant and as a shutdown cooling system that removes decay heat generated from reactor fuel after the reactor shuts down. It also has a function (see Patent Document 1).

  When operating the residual heat removal system as one of the emergency core cooling systems, it is necessary to inject the cooling water flow rate according to the reactor pressure within the specified time at the time of the reactor coolant loss accident. Must be below the specified pump head.

  On the other hand, when operating as a shutdown cooling system, especially when performing fuel replacement work when the reactor is shut down, it is efficient to check the core fuel and replace the fuel while minimizing the shaking and turbidity of the reactor water. Therefore, it is necessary to adjust the system flow rate of the residual heat removal system to the minimum required flow rate within a range that does not hinder cooling.

  The suction side of the residual heat removal system pump is branched from the suction pipe of the reactor coolant recirculation system pump connected to the reactor pressure vessel, and the water source of the emergency core cooling system connected during normal plant operation The suppression pool is separated by a stop valve for switching the water source. The reactor coolant is branched from the suction pipe of the reactor coolant recirculation pump, then pressurized by the residual heat removal system pump, cooled by the residual heat removal system heat exchanger, and then recycled to the reactor coolant. It joins the discharge pipe of the system pump and returns to the reactor pressure vessel. There is an injection valve on the injection pipe to the reactor pressure vessel of the residual heat removal system.

  The injection piping that supplies water to the reactor pressure vessel shares the functions of the emergency core cooling system and the shutdown cooling system, and when starting up as the emergency core cooling system, the injection valve is automatically Then, it is fully opened and cooling water is injected into the reactor pressure vessel. On the other hand, when operating as a cooling system during stoppage, the flow rate is adjusted by remote manual operation of the injection valve. Therefore, the injection valve on the injection pipe must satisfy both the flow rate and differential pressure conditions at the time of the accident and the flow rate and differential pressure conditions at the time of reactor shutdown.

Since the reactor coolant temperature drop rate must be kept below the design value during shutdown cooling system operation, the water flow rate to the heat exchanger is adjusted by the opening of the heat exchanger bypass valve. In particular, when the temperature of the reactor coolant immediately after the reactor shutdown is high, it is necessary to reduce the flow rate of water to the heat exchanger. In some plants, a throttle function is also added to the heat exchanger side valve, and it is possible to directly adjust the water flow rate to the heat exchanger side, but the heat exchanger side valve has a throttle function. In plants that do not, only the heat exchanger bypass flow rate is adjusted.
Japanese Patent Publication No. 64-6716

  When the system flow rate is reduced during operation in the cooling system at the time of stoppage, it is necessary to operate the injection valve at a low opening degree, and repair work by erosion of the valve is a burden. In order to prevent erosion, it is necessary to relax the flow rate and differential pressure conditions of the injection valve. As a countermeasure, there is a plan to add a flow adjustment orifice or throttle valve upstream or downstream of the injection valve of the residual heat removal system. The margin of pressure loss with respect to the pump head defined as the emergency core cooling system is limited, and a throttle mechanism having a sufficient differential pressure cannot be added. In addition, additional installation of a large-diameter valve or orifice may be difficult due to layout restrictions.

  In addition, when adjusting the temperature drop rate of the reactor coolant when the reactor is shut down, it is necessary to adjust the water flow rate to the heat exchanger while keeping the system flow rate constant. In a plant with only a flow rate adjustment function, it is difficult to adjust the water flow rate on the heat exchanger side.

  The present invention has been made to solve the above problems, and in the residual heat removal system of a boiling water reactor, prevents erosion of the injection valve within the range of the pump head defined as an emergency core cooling system. It is an object of the present invention to provide an apparatus and method, and an apparatus and method for adding a function of easily adjusting the system flow rate and adjusting the temperature of the reactor coolant.

In one aspect of the present invention, to remove the residual heat by circulating coolant in the reactor during reactor shutdown in a boiling water reactor, to inject the water in the suppression pool into the reactor during a loss of coolant accident In the residual heat removal system, a heat exchanger that removes heat from the coolant, a heat exchanger water pipe that communicates with the heat exchanger, and a heat exchanger water that is disposed on the heat exchanger water pipe A heat exchanger bypass pipe that bypasses the heat exchanger by branching from the valve, the heat exchanger bypass pipe, the heat exchanger bypass valve disposed on the heat exchanger bypass pipe, and the heat exchanger An injection pipe that joins the coolant that has passed through the water flow pipe and the coolant that has passed through the heat exchanger bypass pipe and injected it into the nuclear reactor, an injection valve disposed on the injection pipe, and the heat exchanger passage Branch from the water pipe and connect the heat exchanger water valve. Yes and the heat exchanger through a water valve bypass piping path to also be joined with the heat exchanger water passage pipe, and the heat exchanger through a water valve bypass valve arranged in the heat exchanger through a water valve bypass on piping, the The flow rate of the heat exchanger and the flow rate of the heat exchanger bypass pipe are controlled by adjusting the opening degree of the heat exchanger water passage valve bypass valve and the opening degree of the heat exchanger bypass valve. It is comprised as follows.
In another embodiment of the present invention, when the boiling water reactor is shut down, the coolant in the reactor is circulated to remove residual heat, and the water in the suppression pool is passed into the reactor in the event of a coolant loss accident. In the residual heat removal system to be injected, a heat exchanger for removing heat of the coolant, a heat exchanger water passage pipe communicating with the heat exchanger, and a heat exchanger disposed on the heat exchanger water passage pipe A heat exchanger valve, a heat exchanger bypass pipe branched from the heat exchanger water pipe and bypassing the heat exchanger, a heat exchanger bypass valve disposed on the heat exchanger bypass pipe, and the heat An injection pipe that joins the coolant that has passed through the exchanger water-passing pipe and the coolant that has passed through the heat exchanger bypass pipe to inject into the reactor, an injection valve disposed on the injection pipe, and the heat exchange The heat exchanger water supply valve branched from the water supply water pipe A heat exchanger water valve bypass pipe that bypasses and merges with the heat exchanger water pipe, and a heat exchanger water valve bypass valve disposed on the heat exchanger water valve bypass pipe. The flow rate of the heat exchanger and the heat exchanger bypass are adjusted by adjusting the opening of the heat exchanger water passage valve bypass valve, the opening of the heat exchanger bypass valve, and the opening of the injection valve. The flow rate of the piping and the flow rate of the injection valve are configured to be controlled.

In another embodiment of the present invention, when the boiling water reactor is shut down, the coolant in the reactor is circulated to remove residual heat, and the water in the suppression pool is passed into the reactor in the event of a coolant loss accident. In the operation method of the residual heat removal system to be injected, the residual heat removal system includes a heat exchanger that removes heat of the coolant, a heat exchanger water pipe that communicates with the heat exchanger, and the heat exchanger passage. A heat exchanger water supply valve arranged on the water pipe, a heat exchanger bypass pipe branched from the heat exchanger water supply pipe to bypass the heat exchanger, and arranged on the heat exchanger bypass pipe and a heat exchanger bypass valve, the injection pipe for injecting into the heat exchanger through water piping coolant and is combined with coolant which has passed through the heat exchanger bypass piping passing through to the reactor, on the injection pipe The arranged injection valve and the heat exchanger water piping Et branched and heat exchanger through a water valve bypass pipe merges with bypass to also the heat exchanger water flow pipe the heat exchanger through a water valve, the disposed in the heat exchanger through a water valve bypass on pipe A heat exchanger water valve bypass valve, and the operation method adjusts the coolant temperature in the reactor by adjusting the opening of the heat exchanger water valve bypass valve; Adjusting the flow rate of the coolant passing through the injection valve by adjusting the opening of the heat exchanger bypass valve.

In another embodiment of the present invention, when the boiling water reactor is shut down, the coolant in the reactor is circulated to remove residual heat, and the water in the suppression pool is passed into the reactor in the event of a coolant loss accident. In the operation method of the residual heat removal system to be injected, the residual heat removal system includes a heat exchanger that removes heat of the coolant, a heat exchanger water pipe that communicates with the heat exchanger, and the heat exchanger passage. A heat exchanger water supply valve arranged on the water pipe, a heat exchanger bypass pipe branched from the heat exchanger water supply pipe and bypassing the heat exchanger, and arranged on the heat exchanger bypass pipe and a heat exchanger bypass valve, the injection pipe for injecting into the heat exchanger through water piping coolant and is combined with coolant which has passed through the heat exchanger bypass piping passing through to the reactor, on the injection pipe The arranged injection valve and the heat exchanger water piping Et branched and heat exchanger through a water valve bypass pipe merges with bypass to also the heat exchanger water flow pipe the heat exchanger through a water valve, the disposed in the heat exchanger through a water valve bypass on pipe A heat exchanger water passage valve bypass valve, and the operation method includes adjusting the opening degree of the heat exchanger water passage valve bypass valve and the opening degree of the heat exchanger bypass valve in the reactor. Adjusting the rate of decrease in the coolant temperature, and adjusting the flow rate of the coolant passing through the injection valve by adjusting the opening of the injection valve.

  According to the present invention, in a residual heat removal system of a boiling water reactor, an apparatus and method for preventing erosion of an injection valve within the range of a pump head defined as an emergency core cooling system, and adjustment of a system flow rate It is possible to provide an apparatus and method for adding a function of easily adjusting the temperature of the reactor coolant.

  Embodiments of a residual heat removal system according to the present invention will be described below with reference to the drawings.

[First Embodiment]
First, a first embodiment of a residual heat removal system according to the present invention will be described with reference to FIG. The suction side of the residual heat removal system pump 6 branches off from the suction pipe 22 of the reactor coolant recirculation system pump 7 connected to the reactor pressure vessel 10 and is connected during normal operation of the plant (reactor). The suppression pool 19 which is the water source of the emergency core cooling system is separated by the emergency core cooling system water source side water source switching stop valve 21.

  After the reactor coolant branches off from the suction pipe 22 of the reactor coolant recirculation pump 7, the reactor coolant is pressurized by the residual heat removal system pump 6 through the reactor-side water source switching stop valve 20, and the heat exchanger 1. The heat is removed and cooled. Thereafter, it passes through the injection pipe 13, joins the discharge pipe 14 of the reactor coolant recirculation system pump 7, and returns to the reactor pressure vessel 10. An injection valve 5 is arranged on the injection pipe 13 to the reactor pressure vessel 10 of the residual heat removal system. The system flow rate is measured by the flow meter 8 on the injection pipe 13.

  The coolant that has passed through the residual heat removal system pump 6 is branched by the heat exchanger bypass pipe 12 on the upstream side of the heat exchanger 1, and the heat exchanger bypass pipe 12 is connected to the flow meter 8 on the downstream side of the heat exchanger 1. The coolant again passes through the heat exchanger 1 on the upstream side. A heat exchanger bypass valve 4 is disposed in the heat exchanger bypass pipe 12.

  A heat exchanger inlet valve (heat exchanger water passage valve) 2 is arranged in a heat exchanger inlet pipe (heat exchanger water passage pipe) 11 on the inlet side of the heat exchanger 1, and this heat exchanger inlet valve 2 is connected to the heat exchanger inlet valve 2. A heat exchanger inlet valve bypass pipe (heat exchanger water-pass valve bypass pipe) 16 is arranged so as to bypass, and a heat exchanger inlet valve bypass valve (heat exchanger water-pass water) is provided in the middle of the heat exchanger inlet valve bypass pipe 16. A valve bypass valve) 15 is arranged. On the outlet side of the heat exchanger 1, a heat exchanger outlet valve (heat exchanger water passage valve) 3 is arranged.

  An injection valve bypass pipe 17 is arranged around the injection valve 5 on the injection pipe 13 of the residual heat removal system, and an injection valve bypass valve 18 is arranged in the middle of the injection valve bypass pipe 17.

  According to the present embodiment, when the residual heat removal system is operated as a shutdown cooling system when the reactor is shut down, the injection valve bypass valve 18 checks the indicated value of the flow meter 8 while the injection valve 5 is closed. When adjusting the flow rate and operating as an emergency core cooling system, the injection valve 5 is used as in the conventional case.

  Since the injection valve bypass pipe 17 has a smaller diameter than the injection pipe 13 and the injection valve bypass valve 18 can be adjusted at a low flow rate, the system resistance when the injection valve 5 is allowed to flow in the event of a coolant loss accident is reduced. The flow rate can be adjusted at a low flow rate and a high differential pressure when the reactor is stopped while minimizing the increase, and erosion of the injection valve 5 can be prevented. It is also possible to install a flow restricting orifice on the injection valve bypass pipe 17 and adjust the system flow rate by the orifice.

  Furthermore, in order to adjust the temperature drop rate of the reactor coolant when the reactor is shut down, the heat exchanger inlet valve 2 is closed, and the indicated value is indicated by the thermometer 9 installed in the suction pipe 22 of the reactor recirculation pump 7. It is also possible to adjust the water flow rate to the heat exchanger 1 by checking the opening degree of the heat exchanger inlet valve bypass valve 15.

  Thereby, it becomes possible to adjust the temperature drop rate of the reactor coolant together with the heat exchanger bypass valve 4. In addition, instead of providing the heat exchanger inlet valve bypass pipe 16 and the heat exchanger inlet valve bypass valve 15, a heat exchanger outlet valve bypass pipe (heat exchanger water-pass valve bypass pipe. And a heat exchanger outlet valve bypass valve (heat exchanger water-passage valve bypass valve, not shown) may be provided. It is also possible to install a flow restriction orifice on the heat exchanger outlet valve bypass pipe and adjust the system flow rate by the orifice.

  In this embodiment, an interlock that is opened by a coolant loss accident signal is added to the injection valve bypass valve 18 in the same manner as the injection valve 5, and is opened at the time of an accident. As a result, when the reactor coolant is lost, water is also passed to the injection valve bypass pipe 18 side, so that the flow rate of water supplied to the injection valve 5 is reduced and the pressure difference of the injection valve 5 is reduced.

  Furthermore, the heat exchanger inlet valve bypass valve 15 can be opened when a coolant loss accident occurs. In this case as well, the differential pressure at the heat exchanger inlet valve 2 similarly decreases.

  Thereby, since system resistance falls, the tolerance of system resistance with respect to the pump head prescribed | regulated as an emergency core cooling system can be expanded. When the tolerance of system resistance increases, for example, when remodeling that increases system resistance for other purposes, restrictions on system resistance increase for piping whose routing is changed, and when residual heat removal system equipment is replaced It becomes possible to widen the tolerance of required conditions such as differential pressure.

[Second Embodiment]
A second embodiment of the residual heat removal system according to the present invention will be described with reference to FIGS. The same or similar components as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted.

  In the second embodiment, the control device 30 automatically controls the temperature reduction rate of the reactor coolant in the first embodiment. For this purpose, the heat exchanger 1 is cooled by the heat exchanger inlet valve bypass valve 15 according to the temperature reduction rate calculated from the measured value of the thermometer 9 installed in the suction pipe 22 of the reactor recirculation pump 7. Adjust the ability. As shown in the configuration of the control interlock in FIG. 3, if the opening degree of the heat exchanger inlet valve bypass valve 15 is changed, it is necessary to readjust the system flow rate. Accordingly, the operation of adjusting the opening degree of the heat exchanger bypass valve 4 and the injection valve 5 is repeatedly performed.

  FIG. 3 shows the procedure in the second embodiment of the cooling mode when the residual heat removal system shown in FIG. 2 is stopped. In step S1, the reactor coolant temperature T measured by the thermometer 9 is read. In step S2, the reactor coolant temperature reduction rate is calculated based on the reactor coolant temperature T. In step S3, it is determined whether or not the reactor coolant temperature reduction rate is equal to or higher than a predetermined set value. If the reactor coolant temperature reduction rate is equal to or higher than the predetermined set value, the opening degree of the heat exchanger inlet valve bypass valve 15 is decreased in step S4. When the reactor coolant temperature reduction rate is less than the predetermined set value in step S3, the opening degree of the heat exchanger inlet valve bypass valve 15 is increased in step S5.

  After step S4 or step S5, the residual heat removal system flow rate F measured by the flow meter 8 is read in step S6, and in step S7, the residual heat removal system flow rate F is greater than or equal to a predetermined set value. Is judged. If the residual heat removal system flow rate F is greater than or equal to a predetermined set value, the opening degree of the heat exchanger bypass valve 4 is decreased in step S8. If the residual heat removal system flow rate F is less than the predetermined set value in step S7, the opening degree of the heat exchanger bypass valve 4 is increased in step S9.

  After step S8 or step S9, the process returns to step S1 and is repeated thereafter.

  According to this embodiment, cooling can be performed at a constant flow rate and a stable flow rate.

  This makes it possible to cool the reactor coolant at a temperature drop (decrease) rate that is less than or equal to the specified value when the reactor is shut down, thereby shortening the reactor shutdown period and the reactor shutdown period. It is.

[Third Embodiment]
A third embodiment of the residual heat removal system according to the present invention will be described with reference to FIGS. The same or similar components as those in the second embodiment are denoted by the same reference numerals, and redundant description is omitted.

  In this embodiment, as shown in the configuration of the control interlock in FIG. 4, the temperature reduction rate of the reactor coolant is controlled by the heat exchanger inlet valve bypass valve 15 and the heat exchanger bypass valve 4, and the injection valve 5. Adjust the flow rate with.

  FIG. 4 shows the procedure in the third embodiment of the cooling mode when the residual heat removal system shown in FIG. 2 is stopped. In step S11, the reactor coolant temperature T measured by the thermometer 9 is read. In step S12, the reactor coolant temperature reduction rate is calculated based on the reactor coolant temperature T. In step S13, it is determined whether or not the reactor coolant temperature reduction rate is equal to or higher than a predetermined set value. When the reactor coolant decelerating rate is equal to or higher than a predetermined set value, the opening degree of the heat exchanger bypass valve 4 is increased in step S14, and when the heat exchanger bypass valve 4 is fully opened, the heat exchanger The opening degree of the inlet valve bypass valve 15 is decreased. If the reactor coolant temperature reduction rate is less than the predetermined set value in step S13, the opening degree of the heat exchanger inlet valve bypass valve 15 is increased in step S15, and the heat exchanger inlet valve bypass valve 15 is When fully open, the opening degree of the heat exchanger bypass valve 4 is decreased.

  After step S14 or step S15, the residual heat removal system flow rate F measured by the flowmeter 8 is read in step S16, and in step S17, whether the residual heat removal system flow rate F is greater than or equal to a predetermined set value. Is judged. If the residual heat removal system flow rate F is greater than or equal to a predetermined set value, the opening of the injection valve 5 is decreased in step S18. If the residual heat removal system flow rate F is less than the predetermined set value in step S17, the opening of the injection valve 5 is increased in step S19.

  After step S18 or step S19, the process returns to step S11 and is repeated thereafter.

  According to the present embodiment, the reactor coolant can be cooled at a stable flow rate at a predetermined temperature reduction rate or less while utilizing the throttle function of the injection valve 5.

1 is a system diagram showing a residual heat removal system according to a first embodiment of the present invention. The systematic diagram which shows the residual heat removal system which concerns on the 2nd Embodiment of this invention. The flowchart which shows the procedure of the automatic control of the cooling mode at the time of a stop of the residual heat removal system which concerns on the 2nd Embodiment of this invention. The flowchart which shows the procedure of the automatic control of the cooling mode at the time of a stop of the residual heat removal system which concerns on the 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Heat exchanger, 2 ... Heat exchanger inlet valve (heat exchanger water valve), 3 ... Heat exchanger outlet valve (heat exchanger water valve), 4 ... Heat exchanger bypass valve, 5 ... Injection valve , 6 ... Residual heat removal system pump, 7 ... Reactor coolant recirculation system pump, 8 ... Flow meter, 9 ... Thermometer, 10 ... Reactor pressure vessel, 11 ... Heat exchanger inlet piping (heat exchanger water flow Piping), 12 ... heat exchanger bypass piping, 13 ... injection piping, 14 ... reactor coolant recirculation system return piping, 15 ... heat exchanger inlet valve bypass valve (heat exchanger water supply valve bypass valve), 16 ... Heat exchanger inlet valve bypass pipe (heat exchanger water valve bypass pipe), 17 ... injection valve bypass pipe, 18 ... injection valve bypass valve, 19 ... suppression pool, 20 ... reactor side water source switching stop valve, 21 ... Emergency core cooling system water source side water source switching stop valve, 22 ... Reactor recirculation system pump suction pipe 30 ... control device

Claims (9)

In the residual heat removal system that removes residual heat by circulating coolant in the reactor when the boiling water reactor shuts down, and injects water from the suppression pool into the reactor in the event of a loss of coolant,
A heat exchanger that removes heat from the coolant;
A heat exchanger water pipe communicating with the heat exchanger;
A heat exchanger water valve arranged on the heat exchanger water pipe;
A heat exchanger bypass pipe that branches off from the heat exchanger water pipe and bypasses the heat exchanger;
A heat exchanger bypass valve disposed on the heat exchanger bypass pipe;
An injection pipe for joining the coolant passing through the heat exchanger water- passing pipe and the coolant passing through the heat exchanger bypass pipe and injecting the coolant into the reactor;
An injection valve disposed on the injection pipe;
A heat exchanger water valve bypass pipe branching from the heat exchanger water pipe and bypassing the heat exchanger water valve and joining the heat exchanger water pipe ;
A heat exchanger water valve bypass valve disposed on the heat exchanger water valve bypass pipe;
I have a,
The flow rate of the heat exchanger and the flow rate of the heat exchanger bypass pipe are controlled by adjusting the opening degree of the heat exchanger water passage valve bypass valve and the opening degree of the heat exchanger bypass valve. That it is configured,
Residual heat removal system. A temperature detector for detecting the temperature of the coolant in the reactor;
When the temperature decrease rate of the coolant detected by the temperature detector exceeds a predetermined value, the opening degree of the heat exchanger water valve bypass valve is decreased, and the coolant detected by the temperature detector When the rate of temperature decrease is less than a predetermined value, it is configured to increase the opening of the heat exchanger water-passage valve bypass valve,
The residual heat removal system according to claim 1. A flow rate detector for detecting a flow rate of the coolant passing through the water injection valve;
When the coolant flow rate detected by the flow rate detector exceeds a predetermined value, the opening degree of the heat exchanger bypass valve is decreased, and the coolant flow rate detected by the flow rate detector is less than the predetermined value. Is configured to increase the opening of the heat exchanger bypass valve in the case of
The residual heat removal system according to claim 1 or 2, wherein In the residual heat removal system that removes residual heat by circulating coolant in the reactor when the boiling water reactor shuts down, and injects water from the suppression pool into the reactor in the event of a loss of coolant,
A heat exchanger that removes heat from the coolant;
A heat exchanger water pipe communicating with the heat exchanger;
A heat exchanger water valve arranged on the heat exchanger water pipe;
A heat exchanger bypass pipe that branches off from the heat exchanger water pipe and bypasses the heat exchanger;
A heat exchanger bypass valve disposed on the heat exchanger bypass pipe;
An injection pipe for joining the coolant passing through the heat exchanger water-passing pipe and the coolant passing through the heat exchanger bypass pipe and injecting the coolant into the reactor;
An injection valve disposed on the injection pipe;
A heat exchanger water valve bypass pipe branched from the heat exchanger water pipe and bypassing the heat exchanger water valve and joining the heat exchanger water pipe;
A heat exchanger water valve bypass valve disposed on the heat exchanger water valve bypass pipe;
Have
By adjusting the opening of the heat exchanger water valve bypass valve, the opening of the heat exchanger bypass valve, and the opening of the injection valve, the flow rate of the heat exchanger and the heat exchanger bypass pipe Configured to control the flow rate and the flow rate of the injection valve;
Residual heat removal system according to claim. A temperature detector for detecting the temperature of the coolant in the reactor;
When the cooling rate of the coolant detected by the temperature detector exceeds a predetermined value, the opening degree of the heat exchanger bypass valve is increased, and when the heat exchanger bypass valve is fully open, Reduce the opening of the heat exchanger water bypass valve bypass valve,
When the temperature decrease rate of the coolant detected by the temperature detector is less than a predetermined value, the opening degree of the heat exchanger water valve bypass valve is increased, and the heat exchanger water valve bypass valve is further increased. Is configured to reduce the opening of the heat exchanger bypass valve when fully open,
The residual heat removal system according to claim 4. A flow rate detector for detecting a flow rate of the coolant passing through the water injection valve;
When the coolant flow rate detected by the flow rate detector exceeds a predetermined value, the opening of the injection valve is decreased, and when the coolant flow rate detected by the flow rate detector is less than a predetermined value Being configured to increase the opening of the injection valve;
The residual heat removal system according to claim 4 or 5 , characterized in that: The residual heat removal according to any one of claims 1 to 6, wherein the injection valve and the heat exchanger water-passage valve bypass valve are configured to open in the event of a coolant loss accident. system. In the operation method of the residual heat removal system, the coolant in the reactor is circulated when the boiling water reactor is shut down to remove residual heat, and the water in the suppression pool is injected into the reactor in the event of a loss of coolant. ,
  The residual heat removal system is
  A heat exchanger that removes heat from the coolant;
  A heat exchanger water pipe communicating with the heat exchanger;
  A heat exchanger water valve arranged on the heat exchanger water pipe;
  A heat exchanger bypass pipe that branches off from the heat exchanger water pipe and bypasses the heat exchanger;
  A heat exchanger bypass valve disposed on the heat exchanger bypass pipe;
  An injection pipe for joining the coolant passing through the heat exchanger water-passing pipe and the coolant passing through the heat exchanger bypass pipe and injecting the coolant into the reactor;
  An injection valve disposed on the injection pipe;
  A heat exchanger water valve bypass pipe branching from the heat exchanger water pipe and bypassing the heat exchanger water valve and joining the heat exchanger water pipe;
  A heat exchanger water valve bypass valve disposed on the heat exchanger water valve bypass pipe;
Have
  The driving method is
  Adjusting the coolant temperature in the reactor by adjusting the degree of opening of the heat exchanger water valve bypass valve;
  Adjusting the flow rate of coolant through the injection valve by adjusting the opening of the heat exchanger bypass valve;
  A method for operating a residual heat removal system. In the operation method of the residual heat removal system, the coolant in the reactor is circulated when the boiling water reactor is shut down to remove residual heat, and the water in the suppression pool is injected into the reactor in the event of a loss of coolant. ,
  The residual heat removal system is
  A heat exchanger that removes heat from the coolant;
  A heat exchanger water pipe communicating with the heat exchanger;
  A heat exchanger water valve arranged on the heat exchanger water pipe;
  A heat exchanger bypass pipe that branches off from the heat exchanger water pipe and bypasses the heat exchanger;
  A heat exchanger bypass valve disposed on the heat exchanger bypass pipe;
  An injection pipe for joining the coolant passing through the heat exchanger water-passing pipe and the coolant passing through the heat exchanger bypass pipe and injecting the coolant into the reactor;
  An injection valve disposed on the injection pipe;
  A heat exchanger water valve bypass pipe branching from the heat exchanger water pipe and bypassing the heat exchanger water valve and joining the heat exchanger water pipe;
  A heat exchanger water valve bypass valve disposed on the heat exchanger water valve bypass pipe;
  Have
  The driving method is
  Adjusting the rate of decrease in coolant temperature in the reactor by adjusting the opening of the heat exchanger water-passage valve bypass valve and the opening of the heat exchanger bypass valve;
  Adjusting the flow rate of coolant through the injection valve by adjusting the opening of the injection valve;
  A method for operating a residual heat removal system.

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